Joint-custody arrangements for children are commonplace when couples divorce, but works of art rarely get shuttled between two homes. Yet such is the case with Andy Warhol’s Ethel Scull 36 Times (1963), a pivotal example of Warhol portraiture and one of the masterpieces of Pop art included in the recent exhibition “Robert & Ethel Scull: Portrait of a Collection” at Acquavella Galleries in New York. A self-made millionaire who built a taxi empire after going into business with his father-in-law, Robert Scull in many ways created the market for Pop, snapping up the whole of Jasper Johns’s first show and lending support to James Rosenquist and John Chamberlain early in their careers. Then he unloaded many of the works at auction in 1973, raking in a cool (for the times) $2.2 million and earning the enmity of the art world.

But a decade before the honeymoon was over, Scull hired Warhol to paint his wife’s likeness as a present for her 42nd birthday. This was Warhol’s first commissioned portrait and his first montage-style painting, composed of three dozen images of Ethel based on shots snapped in a Times Square photo booth, where the artist acted as director, coaxing his subject into a series of flirtatious poses. “Andy and Ethel were enjoying themselves,” curator Judith Goldman writes in the exhibition catalogue, “two kindred spirits who coveted social celebrity and loved fashion.”

Soon after the auction, the Sculls entered into a bitter divorce battle that raged until Robert’s death, in 1986. In the early ’80s, Ethel asked Warhol what she should do with the portrait, and he recommended giving it to the Whitney Museum, which had shown his portraits from the ’70s in a spectacular exhibition. When Ethel landed in the hospital for back surgery, in 1984, Whitney director Tom Armstrong sent curator Patterson Sims to Ethel’s bedside to ask her to go over the papers and formally make a gift of the work.

“She said, effectively, ‘How do you think Bob will feel about my giving this work away?'” Sims, now a freelance curator and writer, recalls. “And I said, ‘Well, I think he’s probably going to be very angry.'” At which point she signed off on documents bestowing the portrait as a partial and promised gift to the museum.

But after Robert’s death, two years later, Armstrong got a call from Ashton Hawkins, then-general counsel and executive vice president at the Metropolitan Museum of Art, who told him that the taxi tycoon had left the portrait to the Met. As Armstrong remembers the conversation, Hawkins said, “‘I’m sending a truck for our painting.’ And I said, ‘Well, it isn’t your painting, Ashton.'” After Scull died, Armstrong claims, the portrait was not in his inventory, or in his will. “As far as I know, no one has ever seen a document that gives this portrait to the Met,” he adds.

When Armstrong, who is now a consultant at Sotheby’s, took the matter to the Whitney’s board, then-president William S. Woodside said he would handle the dispute. “So alone,” says Armstrong, “without taking me or anyone else, he went to the Metropolitan Museum and met with Punch Sulzberger. He returned from that visit and said, ‘We’re sharing the painting.’ And that was it. He gave it away, and I felt there was nothing I could do about it.” Asked if Woodside was cowed by the Met’s board president, Arthur Ochs “Punch” Sulzberger, who was president and publisher of the New York Times, Armstrong responds, “Let’s just say he was compromised.”

Armstrong insists that the portrait was not in Scull’s estate. “I’m quite sure of that, and secondly it wasn’t his, so he couldn’t give it away. It was a gift from him to her. It’s like my giving you the Brooklyn Bridge.”

Hawkins, however, recalls that there was indeed a will. “It was obviously bequeathed to us because otherwise there would be no discussion.” But in another interview, he noted, “We wanted to do the right thing. Everybody wanted to do the right thing.”

And thus, by the terms of an agreement reached out of court in 1989, the painting divides its time, five years at a stretch, between the Met and the Whitney. “The greater good for the public is probably for the two institutions to own the portrait,” Armstrong admits now, “because two dissimilar publics are going to see it.”